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author | Rafael Mendonca <rafaelmendsr@gmail.com> | 2022-11-18 02:15:34 +0100 |
---|---|---|
committer | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2022-11-18 02:15:34 +0100 |
commit | d1776c0202aac8251e6b4cbe096ad2950ed6c506 (patch) | |
tree | c4170b635e6d736d50a54ce3136b470179098969 | |
parent | tracing: kprobe: Fix potential null-ptr-deref on trace_array in kprobe_event_... (diff) | |
download | linux-d1776c0202aac8251e6b4cbe096ad2950ed6c506.tar.xz linux-d1776c0202aac8251e6b4cbe096ad2950ed6c506.zip |
tracing/eprobe: Fix memory leak of filter string
The filter string doesn't get freed when a dynamic event is deleted. If a
filter is set, then memory is leaked:
root@localhost:/sys/kernel/tracing# echo 'e:egroup/stat_runtime_4core \
sched/sched_stat_runtime runtime=$runtime:u32 if cpu < 4' >> dynamic_events
root@localhost:/sys/kernel/tracing# echo "-:egroup/stat_runtime_4core" >> dynamic_events
root@localhost:/sys/kernel/tracing# echo scan > /sys/kernel/debug/kmemleak
[ 224.416373] kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
root@localhost:/sys/kernel/tracing# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff88810156f1b8 (size 8):
comm "bash", pid 224, jiffies 4294935612 (age 55.800s)
hex dump (first 8 bytes):
63 70 75 20 3c 20 34 00 cpu < 4.
backtrace:
[<000000009f880725>] __kmem_cache_alloc_node+0x18e/0x720
[<0000000042492946>] __kmalloc+0x57/0x240
[<0000000034ea7995>] __trace_eprobe_create+0x1214/0x1d30
[<00000000d70ef730>] trace_probe_create+0xf6/0x110
[<00000000915c7b16>] eprobe_dyn_event_create+0x21/0x30
[<000000000d894386>] create_dyn_event+0xf3/0x1a0
[<00000000e9af57d5>] trace_parse_run_command+0x1a9/0x2e0
[<0000000080777f18>] dyn_event_write+0x39/0x50
[<0000000089f0ec73>] vfs_write+0x311/0xe50
[<000000003da1bdda>] ksys_write+0x158/0x2a0
[<00000000bb1e616e>] __x64_sys_write+0x7c/0xc0
[<00000000e8aef1f7>] do_syscall_64+0x60/0x90
[<00000000fe7fe8ba>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
Additionally, in __trace_eprobe_create() function, if an error occurs after
the call to trace_eprobe_parse_filter(), which allocates the filter string,
then memory is also leaked. That can be reproduced by creating the same
event probe twice:
root@localhost:/sys/kernel/tracing# echo 'e:egroup/stat_runtime_4core \
sched/sched_stat_runtime runtime=$runtime:u32 if cpu < 4' >> dynamic_events
root@localhost:/sys/kernel/tracing# echo 'e:egroup/stat_runtime_4core \
sched/sched_stat_runtime runtime=$runtime:u32 if cpu < 4' >> dynamic_events
-bash: echo: write error: File exists
root@localhost:/sys/kernel/tracing# echo scan > /sys/kernel/debug/kmemleak
[ 207.871584] kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
root@localhost:/sys/kernel/tracing# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff8881020d17a8 (size 8):
comm "bash", pid 223, jiffies 4294938308 (age 31.000s)
hex dump (first 8 bytes):
63 70 75 20 3c 20 34 00 cpu < 4.
backtrace:
[<000000000e4f5f31>] __kmem_cache_alloc_node+0x18e/0x720
[<0000000024f0534b>] __kmalloc+0x57/0x240
[<000000002930a28e>] __trace_eprobe_create+0x1214/0x1d30
[<0000000028387903>] trace_probe_create+0xf6/0x110
[<00000000a80d6a9f>] eprobe_dyn_event_create+0x21/0x30
[<000000007168698c>] create_dyn_event+0xf3/0x1a0
[<00000000f036bf6a>] trace_parse_run_command+0x1a9/0x2e0
[<00000000014bde8b>] dyn_event_write+0x39/0x50
[<0000000078a097f7>] vfs_write+0x311/0xe50
[<00000000996cb208>] ksys_write+0x158/0x2a0
[<00000000a3c2acb0>] __x64_sys_write+0x7c/0xc0
[<0000000006b5d698>] do_syscall_64+0x60/0x90
[<00000000780e8ecf>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fix both issues by releasing the filter string in
trace_event_probe_cleanup().
Link: https://lore.kernel.org/all/20221108235738.1021467-1-rafaelmendsr@gmail.com/
Fixes: 752be5c5c910 ("tracing/eprobe: Add eprobe filter support")
Signed-off-by: Rafael Mendonca <rafaelmendsr@gmail.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
-rw-r--r-- | kernel/trace/trace_eprobe.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c index 5dd0617e5df6..fe4833a7b7b3 100644 --- a/kernel/trace/trace_eprobe.c +++ b/kernel/trace/trace_eprobe.c @@ -52,6 +52,7 @@ static void trace_event_probe_cleanup(struct trace_eprobe *ep) kfree(ep->event_system); if (ep->event) trace_event_put_ref(ep->event); + kfree(ep->filter_str); kfree(ep); } |